Refining apparatus



June 1,1943. F. M. SMITH REFINING APPARATUS Filed June 12, 1939 10 Sheets-She et l INVENTOR iff /ad v 4 1 ATTORNEYS REFINING APPARATUS Filed June 12, 1939 10 Sheets-Sheet 2 INVENTQR ATTORN EYS June 1, 1943. F. M. SMITH REFINING. APPARATUS l0 Sheets-Sheet 3 Filed June 12, 1939 ATTORNEYS June 1, 1943. F; M. SMITH 2,320,755

REFINING APPARATUS Filed June 12, 1939 10 Sheets-Sheet 4 INVENTOR ATT RN EYS June 1, 1943. k F. M. SMITH 2,3

'REFINING APPARATUS Filed June 12, 1939 1O Sheets-Sheet 5 INVEN'I'OR ATTORNEY June 1, 1943. F. M. SMITH 2,320,755

REFINING APPARATUS Filed Jun'e 12, '1939 1o Sheets-Sheet e INVENTOR ATTORNEYS June 1, 1943'. F. M. SMITH 2,320,755

REFINING' 'APPARATU$ I Filed June .12, 1939 l0 Sheets-$heet 7 INVENTOR BY I ATTORNEYS June 1, 1943.

F.; M. SMITH REFINING APPARATUS Filed June 12, 1939v 1O Sheets-Sheet 8 "I l l L h P l h lH." H

ATTORNEYS June 1, 1943.

F. M. SMITH 2,320,755

REFINING' APPARATUS Filed June 12, 1939 10 Sheets-Sheet e INVENTOR I ATTORNEY June 1, 1943. F. -M. SMITH- 2,320,755

REFINING APPARATUS Filed June 12, 1939 10 Sheets-Sheet 10 fry/a INVENTOR ATTORNEYS Patented June 1, 1943 UNETED STATES NT OFFICE 7 Claims.

This invention relates to refining methods and apparatus, and more especially it relates to improved procedure and improved apparatus for refining pulverulent or granular material.

For the purpose of illustration, the invention is shown herein in its application to the refining of powdery starch. The refining of starch is of great utility in the candy industry where shallow wooden trays of powdered starch are impressed with intaglio designs and then used as matrices for the forming and aging of fondant centers, the latter subsequently being coated or covered with chocolate or other edible confection. The starch is used over and over, and each time after the candy centers are removed, the starch requires to be refined to remove therefrom any dirt, dust, wood splinters, and candy particles, and to reduce any starch lumps t to particle size that is substantially uniform with the remainder of the starch, or to remove said lumps entirely. In the present invention the starch not only is refined, but is given the proper temperature and proper moisture content required for most eiiicient use in the manufacture of candies of various kinds and consistencies.

The chief objects of the invention are to provide in a superior manner for the cleaning, drying', and conditioning of pulverulent material; to provide apparatus for the foregoing purpose that will operate efficiently at relatively high speed so as to have a large capacity; to provide apparatus wherein the material being treated is concurrently screened and aerated; to provide apparatus of the character mentioned wherein the same medium is used for cooling the material that is used for heating and drying the same; to provide apparatus of the character mentioned wherein the escape of material is prevented, thus making for improved working conditions; and to provide connections between relatively moving elements within the apparatus, which connections do not require to be lubricated. Additional objects include the provision of apparatus that has few moving parts: that will have low maintenance cost; that will be noiseless in operation; that is readily synchronized to operate with a mogul; and that will be safe to operate. Other objects will be manifest as the specification proceeds.

Of the accompanying drawings:

Figure l is a side elevation of a starch handling apparatus comprising one embodiment of the invention;

Figure 2 is a front end elevation thereof as viewed from the right of Figure 1, parts being broken away to reveal a portion of the mechanism thereof;

Figure 3 is a vertical section of the refining and drying unit of the apparatus shown in Figures 1 and 2, and the work therein;

Figure .3a is a transverse Vertical sectional detail taken on the line 3a3a of Figure 3;

Figure 4 is a section similar to Figure 3 of an improved refining and drying unit constituting another embodiment of the invention;

Figure 5 is a section, on a larger scale, on the line 5-5 of Figure 4;

Figure 6 is a section on the line 66 of Fi ure 4;

Figure 7 is a section on the line 1-1 of Figure 4;

Figure 8 is a section on the line 8-8 of Figure 4;

Figure 9 is a section, on a larger scale, on the line 9-9 of Figure 6;-

Figure 10 is a detail sectional View through a modified cascade plate such as is used on the vibratory structures of the refining apparatus;

Figure 11 is a side elevation of another embodiment ofthe refining and drying unit of the apparatus;

Figure 12 is a vertical longitudinal section therethrough; and r v Figure 13 is a vertical transverse section through the refining unit taken on the line Iii-I3 of Figure 12.

Referring to the drawings, the complete apparatus shown in Figures 1 and 2 comprises a refining and drying unit, generally designated 20, and a mogul 2|. The latter is an apparatus that is in common use inthe candy industry, and since the present invention only indirectly relates thereto, only a brief description thereof need be given. Refined powdered starch is delivered to the top of the mogul 2| through a chute 22. Interiorly of the mogul the starch is deposited in trays and impressed with intaglio designs that subsequently are filled with fondant, the latter operation being effected after the trays are removed from the mogul. After the fondant has set or aged, the trays, containing the starch and fondant pieces, are emptied within the mogul where separation of the starch and fondant pieces is effected, the latter then being removed therefrom for further treatment. The used starch from the trays, which at this time may be dirty and lumpy and contain particles of fondant, falls into a trough 23 in the bottom of the mogul, in

which trough is a driven feed screw 24 that impels the starch longitudinally thereof out of the mogul, and delivers it into a hopper 25. Operating within the hopper is a driven, endless, bucket elevator 26 that removes the dirty starch from said hopper, carries it to an elevated position, and dumps it into a chute 2'! that extends downwardly to a trough 28 that extends to the interior of the refining unit 2%), there being a driven feed screw 29, Figure 3, located in said trough for impelling the starch longitudinally thereof into said refining unit. The details of the refining unit, presently will be described.

Dirt, dust, lint, and other lighter than air impurities in the starch are removed therefrom in the refiner by means of air currents that are induced by means of a suction fan 3| in communication with the interior of the refiner at the top thereof, said fan being driven by a motor 32.

Air withdrawn from the refiner by the fan 31 is discharged thereby into a duct 33 that extends to the usual cyclone separator 34 wherein the dirt and other foreign matter is removed from the air, the latter then passing to the atmosphere. The starch, after being refined in the apparatus 20, flows into a trough .35 at the bottom thereof, which trough extends to a hopper 36 exteriorly of the refiner, there being a driven feed screw 31 in said trough for impelling the starch longitudinally thereof to said hopper. Operating within the hopper is a driven, endless, bucket elevator 38 that removes the refined starch from said hopper, carries it to an elevated position, and dumps it into the receiving end of the chute 22 hereinbefore mentioned, whereby it is returned to the mogul 2! for re-use as described. This cycle of use, followed by refining of the starch, is repeated as long as the apparatus operates.

Referring now to Figure 3 of the drawings, it

will be seen that the refining unit 20 of the apparatus comprises a substantially closed housing 40 that is provided at suitable regions with glazed doors 4|, ll through which the operation of the refiner may be observed, and which provide access to the interior of the housing when necessary or desired. Adjacent the bottom of the housing the lateral walls thereof are formed with openings or ports 62, 42 through. which air for refining the starch is drawn, Interiorly of the housing at, near the bottom thereof, are heating coils 43 that are heated by means of steam supplied from any convenient source (not shown).

Positioned above the coils 43 is a vibratory structure generally designated AB, and positioned above the latter, in spaced relation thereto, a second vibratory structure designated M, said structures being adapted to sift or screen powdered starch that passes therethrough and thereover as will be explained. For pendulously supporting said vibratory structures, portions thereof (not shown) project through apertures in the respective lateral walls of the housing and are engaged by flexible hangers (not shown) that are secured to the exterior of the housing, said hangers and apertures being enclosed by cover plates 48, 48, Figures 1 and 2, so that the housing is dust-proof. The vibratory structures 46, 41 extend transversely of the housing from one side thereof to the other, and suitable packing, such as woolskin (not shown) may be interposed between the sides of said structures and the lateral walls of the housing to prevent the passage of air therebetween. The ends of the vibratory structures are spaced somewhat from the end walls (front and rear) of the housing, and said structures are somewhat longitudinally inclined so that the starch will move longitudinally thereof toward their lower ends as the result of the vibration thereof. Thus, the starch is fed onto the upper structure 41 at the upper end thereof, whence it moves to the lower end thereof and passes therefrom onto the adjacent end portion of lower structure 56, which is the uppermost end of the latter. After traversing the length of the structure 45, the starch, now separated into refined stock and tailings, passes therefrom and falls by gravity, the refined stock into a chute '59 that extends to the trough 35 previously described, the tailings into a suitable receptacle 5B for subsequent disposal.

For effecting vibration of the vibratory strucl m the vibratory structure.

the free end of a pitman 52 that has its other end "connected to an eccentric 53 mounted upon a driven shaft 54 that is journaled in the housing i. The shaft 54 is provided with a pulley 55 that is connected by a belt 56 to a pulley 51 that is mounted upon the shaft of an electric motor 58, the latter being mounted in a dust-proof compartment 59 within said housing. The pitman 52 is connected to the vibratory structure 46 by means of a flexible connection that comprises a metal bracket tfi'secured to the top of framework of the vibratory structure, and a fiexible sleeve of rubber or other suitable material 6| carried by said bracket, the pitman 52 being secured in said sleeve. The arrangement is such as to enable the pitman to move angularly relatively of the bracket and frame-work, and the connection does not require lubrication such as might become fouled by the dust that is prevalent within the refiner. In like manner the framework of the upper vibratory structure 4! is provided at its bottom with an identical flexible connection to which is connected one end of a pitman 62, the other end of the latter being connected to an eccentric 83 on the shaft 54. The arrangement enables bothvibratory structures 46, 41 to be reciprocated in a direction that is longitudinal with relation to the housing, whenever the motor 55 is in operation. The shaft 54 and eccentrics 53, 63 thereon are substantially enclosed by a wall 6 that is suitably apertured to enable the pitmans 52, 62 to extend therethrough.

The upper vibratory structure 41 comprises a, pair of sieves or screens 66, 61 of which screen 65 covers substantially the upper end portion of the structure and screen 6'! cover substantially the lower end portion thereof, the arrangement being such that the dirty starch fed into the refiner through trough 28 falls first onto screen 55. The screen 86 is of finer mesh than screen 61, being 24 to 28 meshes to the inch whereas screen 67 is but 20 to 22 meshes to the inch. The reason for the differential screen mesh subsequently will be explained. Vibration of structure 4? causes the starch, deposited thereon at the upper end thereof, to move longitudinally thereof to. its lower end someof the starch sifting through the screen and falling therefrom. The starch on the screens 6'6, 67 contains many lumps too large topass through the mesh, and to assist in breaking up such lumps, brush units 88 and 69 are positioned over the respective screens. The brush units 63 and 83 are pendulously supported above the screens on the free ends of a plurality of pivotally mounted arms l0, it! that are swingable to a limited extent in the direction of the reciprocating movement of An abutment member I2 extends transversely of the housing between the adjacent ends of the brush units, said member serving to limit the swinging movement of said brush units, as has been found desirable. Adjustment means shown at H, II is provided for positioning the brush units in optimum proximity to the screens, the ends of' the bristles usually being about A; in. to /2 in. above the screen at the upper or receiving end of the structure, and somewhat closer at the lower or delivery end thereof. Preferably the bristle tufts of the brushes are arranged in transversely disposed rows with the tufts of adjacent rows in staggered relation to each other. The arrangement is such that as the vibratory structure 4! is reciprocated, the bristles of the brush units 68, 69 engage the starch on the screens 66, 61 and assist in breaking up any small lumps therein.

Also carried by the upper vibratory structure 41 are a plurality of plates I4, 14 that extend transversely of the structure from one side thereof to the other below the screens 66, 61.. The plates I4 are arranged in imbricated or overlapping relation, and the series of plates is so inclined that powdery starch, dropping thereon from said screens, will flow by gravity to the lower endof the series of plates as the structure 41 is reciprocated. As shown in Figure 3, the uppermost margin of each plate I4 underlies the lowermost margin of the adjacent plate, said uppermost, underlying margins being upturned toward the overlying plate, but spaced therefrom sufficiently to permit the passage of air therebetween.

The lower vibratory structure 46 is essentially similar to structure 41, but is inclined in the re-' verse direction to the latter, its higher end being adjacent the lower end of structure 41. The structure 46 comprises screens 18, 19 of which screen 18, at the higher end thereof, is 20 to 22 meshes to the inch and screen 79, at the lower end thereof, is 24 to 26 meshes to the inch. Brush units 88, 8! are positioned above the respective screens 13, I9, said brush units being mounted in the same manner as brush units 68, i

69, and' serving the same function, there being an abutment or bumper 82 positioned between the adjacent ends of the brush units to limit the swinging movement thereof. Below the screens I8, '19 the structure 46 carries an inclined series of laterally overlapping plates 83, 83 that are identical to plates I4 of the structure 41. Below plates 83 and parallel thereto is a second series of overlapping plates 84, 84 that are identical with plates I4 and plates 83.

As is shown in Figure 3a., the lower vibratory structure 46 is centrally divided longitudinally to provide a flue 85 through which a portion of the heated air from coils 43 may ascend to the upper vibratory structure without being required to pass through the lower plates 83, 84 and screen 18.

At the lower or delivery end of the vibratory structure 41. is a covered trough 88 into which the unscreened starch falls as it passes off the delivery end of screen El, and extending downwardly from trough 89 is a plurality of spaced apart tubular chutes, such as the chute 89, that remove the starch from said trough. Below the chutes 89, the vibratory structure 46 carries an inclined deflector plate 99 upon which starch from the chutes 39 falls, to be diverted thereby onto the upper end of screen I8. Flexible rubber Walls 9|, 9| span the space between the lower end of chutes 89 and the adjacent portion of structure 46, thus enclosing the space through which the starch falls; yet enabling relative movement between the structures as, 41 due to reciprocation thereof. Preferably there is a flexible rubber apron 92 at the delivery end of the screen 61, the starch passing under said apron to flow into the trough 88. At the lower or delivery end -of the series of overlapping plates 14 is a plate 94 onto which the screened starch flows from the lowermost plate 14, said plate extending between the several chutes, and being downwardly inclined, the delivery margin of said plate 94 being disposed in a covered spout 95, rearwardly of the rearmost flexible wall 9|. Below the spout 95 the lower vibratory structure 4'Iis formed with a curved, downwardly inclined Wall 95, the lower end of which overlies the uppermost plate of the lower series of plates 84. A flexible depending apron 91 rests against the lower end of plate 94, the sifted starch passing under said apron to flow into spout 95. A flexible rubber wall 98 connects the lower end of spout 95 to the adjacent wall of structure 46, thus enclosing the course of the starch that flows from said spout, said flexible wall enabling relative movement of the two vibratory structures. The arrangement is such that the unsifted starch from the screens of the upper vibratory structure 41 flows onto the screen T8 of the lower vibratory structure, the sifted starch from the plates I4 of the upper structure flowing onto the lower plates 84 of the lower vibratory structure.

As previously stated, the dirty starch is fed intothe refiner 29 by the feed screw 29 operating within trough 28, said feed screw being driven from shaft 54 by means of an interposed sprocket chain 99, Figures 1 and 2. Interiorly of the refiner housing 40 the trough 28 is positioned above the uppermost or work-receiving end of the upper vibratory structure 41, the bottom of the trough. having a longitudinally extending opening or slot I99: therein for the starch to fall through. Said opening I90 is provided with a slidably mounted closure member I! by means of which the'width of the opening may be varied. Below the trough 28 the upper end of the vibratory structure 41 is provided with an inclined plate I 92 upon which starch falling from the said trough will strike, the lower margin of plate I02 being positioned at the upper end of screen 66 so that the starch flows onto the latter. Flexible rubber walls I93, I03 connect the bottom of trough 28, at each side of opening I 90 therein, with the top of structure 4'1, thereby enabling relative movement of the trough and vibratory structure without interference to the flow of starch therebetween.

At the lower end of the lower vibratory structure 46, the end plate I95 of the lower series of plates 84 extends beyond the end plate of the series of plates 83, so that the screened starch falling from end plate 83 drops upon end plate I95. The lowermost or delivery margin of the latter is positioned over the open upper end of chute 49 previously described, with the result that against the lowermost margin of the lower plate 83 so that the screened starch passes thereunder in flowing oil said plate. A similar flexible apron II 9 rests against the delivery edge of end plate I95. A delivery end of structure 48 also is formed with a covered trough I91 arranged to receive the tailings that flow thereinto from the lowermost end of screen I9, said trough I91 having an inclined bottom I98 that discharges into a downwardly inclined spout I09, the latter having its delivery end positioned over the receptacle 50 reviously described.

Positioned in the top of the housing 40 is a duct I I2 formed in the bottom of its structure with a plurality of inlet ports H3, H3 through which air, from the interior of the housing, is drawn. At its middle the duct I I 2 communicates with the intake side of suction fan 3| through the agency of a duct H4. At the juncture of ducts H4, H2, the bottom of the latter is formed with a depressed region H5 in the bottom of which are two normally closed valves H6, H6 that open when a determinate quantity of material rests thereon, said material being powdery material dropping from the stream of air that is moving into duct II 4. There is a flexible rubber wall H8 between the lower end of duct II 2 and the lower end of vibratory structure 41, and there is a similar flexible wall I I9 between the upper end of vibratory structure 46 and the top of a low partition I29 at the adjacent end of the heating coils 43. There is a low partition I2I at the opposite end of said heating coils, and a flexible wall I22 connecting the top of said partition with the lower end of lower vibratory structure 46. The wall 64 that partly encloses the shaft 54 and eccentrics 53, 53 is connected by a flexible wall 23 to the top of adjacent lower vibratory structure 46, and is connected by flexible wall I24 to the bottom of adjacent upper vibratory structure 47. The function of the several flexible walls described is to confine the air current in the refiner o that it follows a determinate course.

In the operation of the refiner motors 32 and 58 are constantly driven, and the coils 43 are heated by the admission of steam thereto. Motor 32 drives suction fan 3I and thus creates a rising current of air that enters the housing 43 through the ports 42 near the bottom thereof, and immediately passes over coils 43 whereby it is warmed to the desired temperature, the air being withdrawn from the housing through duct I I2. Motor 58 drives shaft 54, thereby rotating eccentrics 53 and 63,, with the result that upper' and lower vibratory structures 46, 41 are longitudinally reciprocated. Motor 53 also effects the rotation of feed screw 29, through the agency of drive-chain 99, so that dirty starch, delivered to trough 28 from chute 27, is fed into the refiner, said starch falling through the slot I III] in the bottom of said trough and being diverted by the inclined plate I92 onto the receiving end of screen 66 of the upper vibratory structure 41. brates, the starch is caused to flow by gravity toward the lower end thereof, thus passing over screen El. As the starch flows over said screens, the fine particles thereof sift through and fall onto the overlapped plates i4 therebeneath, and the inclination of said plates and the vibratory movement thereof causes the sifted starch to flow by gravity to the lower end of the series of plates, the starch cascading over the gaps that are present between the plates.

At the lower end of vibratory structure 47, the unscreened starch on screen 6'! falls therefrom and passesthrough trough 88 and chutes 89, being diverted by inclined plate 99 at the bottom of the latter into the upper or receiving end of screen I8 of the lower vibratory structure 46. The screened starch from the plates I4 passes through spout 95 and flows onto the upper end of the series of overlapping plates 84. Vibration of structure 48 causes the unscreened starch to flow As the latter viover screens I8, I9 to the lower end of the latter, the starch that sifts through the screens falling onto the overlapping plates 83. At the lower end of screen I9 the tailings flow through chute I09 into receptacle 50. The sifted starch on plates 83 flows therefrom onto end plate IE5, where it mixes with the starch from plates 84 and passes into the chute 49 which removes it from the refiner.

As the starch moves along the vibrating screens 66, 61, I8 and 19, the reciprocatory swinging movement of the latter causes the starch on the screens to engage the bristles of the brushes 68, 69, and 8I the latter thus serving to break up small balls of the starch. Furthermore, the staggered arrangement of the tufts of brush bristles causes the starch to be moved transversely back and forth on the screens, thus producing more effective screening and increasing the capacity of the refiner. The brushes are so set that they engage the starch but not the screens that carry the starch, the arrangement preventing the clogging of the screens by the forcing of starch therethrough.

As the starch is being subjected to the foregoing mechanical treatment, the suction fan is drawing air into the housing 40 through the openings 42 near the bottom thereof, which air moves upwardly within the housing and passes therefrom through the duct I I2 in the top thereof. The air upon entering the housing first passes about the steam heated coils 43 and is warmed thereby to the temperature best suited for the drying of the starch. As the heated air moves upwardly from the coils 43 it passes between the plates 34 of the lower series of overlapping plates, and the plates 83 of series immediately above the latter. Since the screened starch is falling or cascading from each plate to the succeeding lower plate, the air current of necessity passes through falling powdery starch and aerates, dries, and heats the starch. Continuing its rise, the heated air moves counter to the sifted starch falling from the screens I8, I9,

f thereafter passing through the screens I8, 79 and brushes thereabove where it exercises a similar function upon any starch upon said screens. The rising air next encounters the plates I4, screens 66, 61, and brushes 68, 69 of the upper vibrating structure 41 where it picks up therefrom lighter particles, such as dust, lint, wood fibre and the like, and also initiates the aerating, drying, and heating of the starch. The arrangement is such that the sifted starch and the tailings are delivered into the chute 49 and receptacle 59 respectively, and the sifted starch is free of foreign particles and is dried and heated to the extent that it is ready for immediate re-use in the mogul 2| to which it passes. At the top of the housing, the air, laden with the lighter particles, passes into the duct H2 through the openings I I3 in the bottom thereof, and is impelled by the fan 3| into the cyclone 34 where it is cleaned in the usual manner and discharged to the atmosphere. Particles dropped by the air current in ducts H2 and H4 collect in the depressed region II 5 and periodically are dumped back into the refiner by the valves I I5. Because the apertures H3 in the duct H2 are of smaller capacity than the capacity of the duct, the current of air is throttled or slowed down at these points, causing the air current to drop light particles of starch that it may be carrying. The several flexible transverse walls within the housing confine the starch and the air currents to a local region, with the result that the housing is dusttight, and the motor and other moving parts are not fouled by powdery material. Working parts that are exposed to dust, such as the flexible connections between pitmans 52, 62 and the respective vibratory structures, are so constructed as not to be susceptible to fouling by dust. The feature of having the screen 53 of finer mesh than the other screens is for the purpose of keeping the starch on the screen for a longer interval in order that it may be more widely distributed over the screen, whereby improved drying of the starch is effected. The relatively fine mesh of the screen I9 is for the purpose of retarding the air passing therethrough, there being relatively little starch normally on this screen.

. Since the feed screw 23 and the eccentric shaft 54 are both driven by the same motor 58, it will be apparent that the vibratory cycle of the structures 46, 41 is in direct ratio to the speed of feed ofstarch into the refiner through trough 28, with the result that the apparatus readily may be speeded up or slowed down to handle various quantities of starch. Furthermore, the speed of the fan 3i may be regulated to control the flow of air through the refiner, and the temperature of the air also is controllable by means of the heating means described. The invention provides an improved apparatus in which starch is refined by heating, drying and aerating, and it also achieves the other objects set out in the foregoing statement of objects. 1 Referring now to Figures 4 to 9, inclusive, of the drawings, there is shown another embodiment of the invention that differs in some respects from that previously described, especially in the means for collecting the dirt-laden air and conducting it from the housing. This embodiment of the invention comprises a housing I 36 which may have lateral walls of double thickness, including thermal insulation therein, if desired, for conserving the heat within the housing. The housing is provided with the usual glazed doors I3I, I3I, and adjacent its bottom is formed with openings or ports I32, I32 through which air for refining the starch is drawn into the housing. Intericrly of the housing, near the bottom thereof, are heating coils I33, I33 that are heated by steam supplied from any convenient source of supply (not shown).

Positioned above the heating coils I33 is a vibratory structure, generally designated I36, and positioned above the latter, in spacedrelation thereto, is a second vibratory structure 13?, said structures being substantially similar to the vibratory structures 46, 47 previously described, and for the same purpose. As is best, shown in Figures 4, and 8, the vibratory structure I 36 is composed of two identical units disposed side by side,.each of said units comprising vertically disposed lateral frame membersl38, I38. All of said frame members are supported upon a pair of transversely disposed rods I39, I33 that are positioned at the opposite ends of the structure, and

which extend through respective arcuate slots 14!), I40 in the opposite lateral walls of the housing I30. Exteriorly of the housing the projecting ends of the rods I39 are attached to the free, lower ends of respective flexible hangers I4I, preferably constructed of rubber, the upper ends of said hangers being fixedly secured to suitable brackets mounted upon the exterior of the housing, The hangers, and the slots I43 in the hous ing walls, are enclosedby cover plates, M2,..I43. Ereferably layers of woolskin. I43 are interposed between the lateral frame members I38 and the inner surface of the housing to prevent the passage of air and powdered starch therebetween.

For effecting vibration of the structure I33, the tops of the respective units thereof are'prov'ided with respective transversely disposed members I 45- that are connected to the free ends-of respec tive pitmans I46, I46, the other ends of the latter being connected to respective eccentrics I41, 14! that are mounted upon a driven shaft I43 that is journaled in the housing I30, at the front end thereof. The shaft I43 is provided with a pulley I49 that is connected by dual belts I50 to a pulley I5I upon the shaft of an electric motor I52, the latter being mounted within a dust-proof compartment I53 within the housing. Each pit man I46 is connected to the vibratory units of the vibratorystructure- I 36 bymeans of a flexible connection that complises a metal bracket I54 secured to the top offrame member I45, and a rubber sleeve I55 carried by said bracket, the pitman being secured in said sleeve. The flexible connection is-identical with that previously described, and possesses the same advantages as the other. The arrangement is such that the vibratory structure I36 is reciprocated in a longitudinal direction whenever the motor I 52 is in operation. The shaft I48 and ec centrics thereon are enclosed by an apertured wall I53 substantially in the same manner as the similar elements of the previously described embodiment. The framework of the structure I36 also includes cross pieces I56, I56 that assist in supporting sieves or screens I51, I53, the said screens being in all respects similar to screens I8, 13 of the previously described embodiment of the invention. The framework of the structure I36 also carries two inclined series of overlapping metal plates I63, I6I that are substantially identical in structure and function to the plates 63, 84 previously described.

Positioned above the screens I51, I58 are the brush units that are starch on said screens as the latter receiprocate. There are two screens I 51 and two screens I58, and four brush units are. providedjthere being one for each of said screens. For supporting said brush units, four hollow supporting members I64, I64 are positioned above the tend transversely of the housing, the ends of said members being secured to the opposite lateral walls of said housing. Secured to each member I64 are two laterally projecting brackets I65, I65, and adjustably secured to the latter are respective resilient elements I66, usually consisting of coiled springs. Pendulously pivoted to each of the latter are respective swinging arms I61 that swing parallel to the reciprocating movement of the vibratory structure, there being two of said arms for supporting each brush unit. Each of said brush units comprises a centrally disposed, longitudinally extending member I68 to which two arms I6I are pivotally connected, said member I68 having a plurality of transverse, rib-like members I69, I63 secured to the under side thereof, said members I69 carrying downwardly'projecting tuftspof brush bristles III). The transverse members I63 may beef two different lengths arranged in alternation, the longer carrying the greater numberof. tufts. The members I69 are so arranged relatively of each other that the'tufts' on each of themare in staggered relation to the tufts on adjacent members, asindicated in Figure 8. The functionand advantages of thebrush elements previously have been, set forth. i x

provided for engaging the brush units and ex- In other respects the lower vibratory structure I36 is similar to the structure 46 previously described, the delivery end of the structure being provided with a spout I13 for receiving the tailings that drop from the delivery end of screen I58 and directing them into a suitable receptacle I14. The refined starch that flows from the delivery end of the lower overlapping plates I6! falls into the open end of a chute I15 that conducts it from the housing for subsequent use.

Referring now to the upper vibratory structure I31, it will be apparent from reference to Figure 5 that it comprises a pair of units arranged side by side and provided with lateral frame members I18, I18, the latter being supported at opposite 3 ends of the structure upon transverse rods I19, I19. The rods I19 extend through arcuate slots I80, I80, Figure 4, in the lateral walls of the housing I30, being supported from their projecting end portions by flexible hangers I8I. The upper ends of the latter are suspended from brackets I82, and the hangers and brackets are enclosed in suitable cover plates I83. The layers of woolskin I43 previously mentioned extend upwardly between the lateral frame members I18 and the inner surface of the housing.

For effecting vibration of the structure I31, the respective frame members of each unit thereof are connected to each other by respective transversely disposed members such as the member I86, Figure 4, located near the bottom of said frame members. Transverse members I69 are connected to the free ends of respective pitmans I81, the other ends of the latter being connected to respective eccentrics I88 that are mounted upon the driven shaft I48. The free ends of pitmans I81 are connected to the transverse members I83 of the vibratory structure by means of flexible connections, each of which comprises a bracket I89 and a rubber sleeve I90 identical with similar connections previously described. The arrangement is such that vibratory structures I36, I31 are reciprocated in unison. The framework of the structure I31 includes cross pieces I9I, I9I that assist in supporting sieves or screens I92, I93, which screens are similar in all respects to screens 66, 61 of the previously described embodiment of the invention. The framework of the structure I31 also, carries an inclined series of overlapping metal plates, I94, I94 that are substantially similar in structure and function to. the plates 14 of the firstv described embodiment. In addition to the plates I94, the structure I31 includes a second series of overlapping plates I95, I95 that are positioned above, the plates I94, in spaced relation thereto, at the lower end region of the latter, the arrangement being such that the screened starch. dropping through the screens I93 falls solely upon the plates I95. The lower or delivery end of the series of plates I95 is posia tioned above the lowermost plate of the series of plates I94 so that the starch from the upper series is delivered onto the lowermost plate of the lower series. The plate I94 at the delivery end of the lower series has a steeply inclined extension I96, the delivery end of the latter being positioned in a chute I91 at the lower end ofstructure I31. At the delivery end of screens I93 are the flared receiving ends I98 of four cylindrical vertical chutes I99, I99, which chutes extend downwardly through. the inclined extension I96 of the overlapping p lates I95, and discharge from the structure I31 laterally of the chute I91 that discharges the screened starch. The chute I91 is positioned so that starch discharged therefrom flows onto the upper end of lapped plates I6I. Chutes I99 are positioned over an inclined plate 200 on structure I36 that is so positioned that unscreened starch falling thereonto flows onto the upper end of screen I51. Flexible walls of rubber 20I, 20I connectthe adjacent ends of structures I36, I31 and separate the respective passages for starch thereat.

Positioned above the screens I92, I99 are the brush units that engage the starch on said screens as the structure I31 is reciprocated, there being two brush units for the two screens I92 and two brush units for the two screens I93. For supporting said brush units, four hollow supporting members 204, 204 are positioned above the brush units and extend transversely of the housing, their ends being secured in the lateral walls of the housing. Brackets 205 secured to said supports have respective resilient elements 206 adjustably secured to them, said resilient elements having depending arms 291 pendulously secured to their lower ends, there being two arms 201 for each brush unit. Each brush unit comprises a centrally disposed, longitudinally extending member 208 to which two of the arms 201 are pivotally connected, said member 208 having a plurality of transverse rib-like members 299, 209 secured to the under side thereof, said members 209 carrying downwardly projecting tufts of brush-bristles 2I0. The ribs 209 may be of two different lengths and the bristle-tufts 2I0 thereon are in staggered relation in adjacent rows as previously described.

In other respects the upper vibratory structure I31 is similar to the vibratory structure 41 of the previously described embodiment of the invention. At its upper or work receiving end the structure I31 is provided with an inclined plate 2I2, the lower end of which is at the receiving end of the screens I92. The plate 2 I2 is disposed below the slot 2I3 that extends longitudinally of a transverse trough 2 I 4 in the top of the housing, said trough having a feed screw 2I5 therein for impelling untreated or dirty starch into the refiner, said feed screw being mounted upon a driven shaft 2 I6. The latter has driving connection (not shown) with the driven shaft I48. Flexible walls 2 I1 connect the bottom of the trough 2I4 to the upper end, of vibratory structure I31, thus providing a dust-proofpassage for the starch issuing from the slot 213 of said trough.

For withdrawing air from the housing, an exhaust fan 22.0 is mounted in the top thereof, remote from the trough 2I4, said fan being, carried upon a shaft, 22I that extends transversely of the housing, a motor 222 being connected to said shaft exteriorly of the housing. The fan. 229 is positioned centrally of the housing. with relation to the lateral walls thereof, and is partly enclosed by a sheet metal: casing 223, the latter having inlet openings 224 at each side thereof, concentric with the shaft. 224, and having a discharge duct 225 that extends through the housing wall. Exteriorly of the housing the duct 225 connects with an air-cleaning and dust-recovery apparatus (not. shown similar to that previously described; Extending transversely of the interior of housing I30, near the top-thereof. adjacent fancasing 223.is a partition. 226, and. secured to said partition and to the adjacent end wallof the housing are sheet metal walls 221, 221 that extend from the lateral walls of the fan casing tothe sides of the housing and thus provide over the inclined end-wall of the structure I39 7- chambers; f'W Chpeni e 224 of the fan casing constitute respective outlets therefor. At the other end of the housing, in the top thereof and at the near side of trough 2I4, is a transverse chamber 230 that comprises sheet metal walls 23I, 23L Supported by the partition 226 and the adjacent wall 23I of chamber 233 is a plurality, shown as five in number, of sheet metal troughs 232, 232, which troughs are horizontally disposed in spaced-apart parallel relation. The top of the partition 226 is cut away above the tops of the troughs 232, as best shown in Figure 5, to allow air to pass over said troughs and to move into the chambers at opposite sides of the fan casing 223.

Referring now to Figure 9 of the drawings, it will be seen that the upper margins of the troughs 232 are turned inwardly toward each other. Mounted above the spaces between the respective troughs 232 are deflector members 234, 234, which members have the shape of an acute angle in transverse section with the apex of the angle directed upwardly, the lateral marginal portions of the said members being bent inwardlytoward each other, and positioned within the troughs 232, somewhat below the inturned upper margins of the latter. At the outside margins of the outermost troughs 232 of the series are inclined deflector plates 235 that are similar to deflector members 234 at their lower margins, but are not angular in section, the upper margins of plates .passages between the lower margins of the deflector members 234, 235 and the upper margins of the troughs, as indicated by broken-line arrows in Figure 9, which passages are arcuate as the result of the curved margins of the troughs and deflectors. The narrow, curved passages throttle the air streams and cause the latter to drop any starch particles that they may be carrying, the lighter dust particles remaining in suspension in the air so as subsequently to be removed therefrom exteriorly of the refiner. Y

The starch particles dropped by the air streams as described fall into the troughs 232, and for removing the particles from the latter, respective feed-screws 237 are positioned therein, said feedscrews being journaled at one end in the partition 225 and at their other ends in' the near wall 23I of chamber 233. The feed-screws 23'! are rotated in the proper direction to impel the starch particles in the troughs toward the chamber 230, the wall of the latter, at the ends of the troughs, being cut away or apertured to enable the starch to pass therethrough as indicated by the arrow in Figure 4. The starch that collects in the bottom of the chamber 230 may be removed therefrom through the side of the housing. For driving the feed-screws 231, the shaft of each of them is provided with a sprocket 239, disposed within the chamber 230, said sprockets being interconnected by a sprocket chain 240 that passes over and under alternate sprockets. The sprocket chain 240 also is trained about an idler sprocket 24I mounted upon shaft 242 in one end of chamber 230, and about a driving sprocket 243 in the other end of chamber 230. The sprocket 243 is carried upon a short shaft 244 that is journaled in the opposite walls 23I of the chamber, said shaft extending through the chamber wall and carrying a bevel gear 245 on its end exteriorly of the chamber. The bevel gear 245 is meshed with a bevel pinion 246 that is mounted upon a shaft 24'! extending transversely of the housing I30 and journaled in the opposite lateral walls thereof, said shaft having a projecting portion exteriorly of the housing upon which is mounted a pulley 248. The latter is connected to a driving pulley 249 of somewhat smaller diameter, that is mounted upon the exposed end portion of adjacent driven shaft 2I6, by means of a transmission belt 250, Figure 6. The arrangement is such thatthe feed screws 23'! are driven whenever the infeed screw 2I5 is driven.

There is a flexible transverse wall of rubber 252 between the bottom of partition 226 and the top of vibratory structure I31. Similar flexible walls 253, 253 are positioned between the respective ends of the lower vibratory structure I36, and partitions 254, 255 at opposite ends of the heating coils I 33. Other flexible walls, designated 253, are positioned between the apertured wall I59, and the adjacent frame of the upper vibratory structure 831 and lower vibratory structure I36.

This embodiment of the invention functions in substantially the sam manner as the embodiment previously described, the principal difference residing in the improved construction of the means in the top of the refiner for separating starch particles from the heated air, the operation of which previously has been explained.

Referring now to Figure 10 of the drawings, there is shown a cascade plate 263, such as is used with the vibratory, structures of any embodiment of the apparatus, said plate being of modified construction in that means is provided for individually heating it. To this end electrical heating units 26! are mounted upon the under side of the plate, said heating units being enclosed by means of a cover plate 232 so that none of the dust-laden air in the refiner comes into contact with the heating elements. It will be understood that the heated cascade plates 263 may be used on one or both vibratory structures in the refiners, and for one or both series of cascade plates on said vibratory structures. The arrangement provides means for obtaining greater heat within the refiners, and also for readily controlling said heat.

Referring now to Figures 11 to 13 of the draw,- ings, there is shown another embodiment of the invention that is essentially the same as those previously described in the details of its various elements, but-is arranged to deliver the refined starch, in cool, dry condition, which condition is preferable in the manufacture of some kinds of confections. As shown in the drawings, the refiner is positioned partly above and partly below the floor of a building, said floor being designated 284. That portion of the refiner that is positioned above the floor is enclosed in a housing 235, and that portion that is positioned below the floor is enclosed in a housing 236, the latter being attached to the imder side of said floor, which is the ceiling of the lower room. The

interior of housing 265 connects with the interior of housing 236 through the agency of a relatively large opening 261 in the floor, said opening being provided with a grating or gril 258 if desired. The starch refining mechanism in the upper housing 265 is essentially the same a that shown in Figure 5. Said mechanism comprises an upper vibratory structure 213 and lower vibratory structure ZiI, both vibratory, structures comprising screens, brushes, and overlapping cascade plates as previously described. The vibratory structures are vibrated b means of respective pitmans 2i2, 213 that are connected at one end to said structures, and at their other ends are connected to respective eccentrics carried upon a transversely disposed, driven shaft 2'54. The latter is connected by belt 215 to the shaft 2'16 of an electric motor 2?? that is suitably enclosed in a dust-proof compartment 228 interiorly'of the housing 265.

Dirty starch is introduced into the housing 265, from the exterior thereof through the agency of a trough 283 in the top of th housing. Exteriorly of the housing, the dirty starch is dumped into trough 280 from an enclosed endless bucket elevator 281 that extends through the floor 264 to a hopper 282, the latter being associated with a mogul 283 on the floor below. Afeed screw 284, Figure 13, is provided for feeding the starch from the mogul 283 to the hopper 282. Within the trough 283 is a shaft 235 having a feed-screw 285 formed thereon, said feed screw being provided for impelling the starch longitudinally of the trough from the point where it is dumped thereinto by the elevator. A plurality of flexible, tubular chutes 23?, 28'! extend downwardly from the trough 260 and discharge onto the screen of the upper vibratory structure 2'56. The feed-screw-shaft 235 is driven by means of a transmission belt 238 that is trained about a pulley 286 mounted upon a projecting end of shaft 2'53, and a pulley 230 mounted upon a projecting end of shaft 285, remote from the elevator Eat. The other end of shaft 265 carries a pulley 291 that is connected by a transmission belt 262 with a pulley 233, the latter being mounted upon a shaft 234 that carries a sprocket 29c. Sprocket 235 carries the upper end of the endless conveyor 281, the lower end thereof being trained about a sprocket 236 carried by a shaft 297 in the hopper 262. Shaft 29! may be connected to or constitute a part of the feed screw 283 that impels starch from the mogul 283 to said hopper. The arrangement is such that the single motor 2?! serves to drive the feed screw 284, elevator 231, feed screw 286, and shaft 2M, the latter serving to effect reciprocation of the vibratory structures 2'10, 211.

At the delivery end of the lower vibratory structure 2'11, tailings from the screen thereof fall into a chute 300 that delivers them into a receptacle 301 within the housing, from which receptacle they are subsequently removed. The sifted starch from the cascade plates of the lower vibratory structure fall into a plurality of flexible chutes 302, 302 that extend downwardly through the floor 264 and discharge onto the receiving end of another refining mechanism located in the lower housing 266.

The starch refining mechanism in the lower housing 266 is essentially the same as that in upper housing 265, there being an upper vibratory structure 305 and a lower vibratory structure 306, the latter, however, having but one series of cascade plates as compared to the two series in the vibratory structure 211. Reciprocation of the vibratory structures 305, 306 is effected by means of respective pitmans 301, 308 that are connected at one end to said structures, and at their other ends are connected to respective eccentrics carried upon a transversely disposed shaft 309. Exteriorly of the housing 266, the

that is connected by a transmission belt 311 to a pulley 312 carried by the driven shaft 2'14 hereinbefore described, said pulleys 310, 312, and the belt 31] being protected by a casing 313 secured to the side of the housings 265, 266. At the delivery end of the lower vibratory structure 306, the refined starch is discharged into a plurality of flexible chutes 314; 314 that extend through the bottom of the housing and discharge into a trough 3,15 mounted below said housing. EX- tending longitudinally of the trough 315 is a shaft 316 that has a feed screw 311 formed thereon, said feed screw being adapted to impel the starch in the trough to one end thereof, where a downwardly extending delivery chute 318 is provided. The chute 318 discharges the refined starch into the top of the mogul 283 that is positioned therebeneath. For driving the shaft 316 and its feed screw 317, a projecting end of said shaft is provided with a pulley 320 that is connected by a transmission belt 321 to a pulley 322 mounted on the projecting end of driven shaft 309. The arrange'zment'is, such that the motor 211 drives all of the moving mechanisms of this embodiment of the invennon.

The cleaning of the starch and the carrying off of the lint, dirt, and foreign matter therein shaft 309 is provided with a pulley 310, Figure 11, 76

is effected by an upwardly moving current of air in substantially the same manner as in the previously described embodiments of the invention. To this end the bottom of the lower hous ing 266 is formed with an inlet opening 325, Figure 12, of sufiicient size to admit the amount of air required. The air current is induced by a suction fan (not shown) in a casing 325 atop the housing 265, said fan being driven by a motor 321. On its intake side the said fan communicates with the interior of the housing 265 through a duct 328, and interiorly of the housing are suitable bafiles 329 that throttle the air current before it passes into duct 328, and thus causes said air current to drop its heavierpar ticles, as previously described. At the discharge side of the fan is a duct 330 that discharges into a cyclone 331 wherein the dirt and dust is separated from the air current in the usual manner.

Located within the upper housing 265, over the opening 261 in floor 264, are pipe coils 334 through which heated fluid, such as steam, may be passed. The air current in passing the coils 334 becomes heated, and thus transfers the heat to the powdery starch as it moves through the latter, with the result that the starch is thereby dried and conditioned. Located within the lower housing 266, over the opening 325 in the bottom thereof, are pipe coils 336'through which cooling fluid, such as cold water, may be passed. The arrangement is such that air drawn into lower housing 266 is cooled below atmospheric temperature, and thus removes heat from the starch that is traversing the vibratory structures 305, 306, as it moves upwardly through the latter. The arrangement is such that the completely refined starch delivered from the chute 3:8 is in the cool condition best suited for the manufacture of certain kinds of candy Other modification may be resorted to Without departing from the spirit of the invention,- or the scope thereof as defined by the appended claims, which{ are not limited wholly to the specific construction shown, or exact procedure described. 1

What is claimed is:

1. Apparatus for refining pulverulent material, said apparatus comprising a pair of oppositely inclined vibratory structures disposed one above the other, each of said structures comprising a downwardly inclined screen and a downwardly inclined series of overlapped plates disposed below said screen and adapted to receive the material passing therethrough, means for leading material from the lower end of said upper screen to the upper end of said lower screen, an auxiliary series of overlapped plates associated with the lowest portion of said lower vibratory structure below the series of overlapped plates forming part of said lower vibratory structure, said series of overlapped plates being adapted to cascade material from the upper to the lower ends thereof, means for leading screened particles from the lower end of said upper series of overlapped plates to the upper end of said auxiliary series of overlapped plates,

and means for passing a countercurrent of airthrough said vibratory structures to clean and dry the pulverulent material whereby said auxiliary series of overlapped plates aids in cleaning and drying the screened material.

2. In apparatus for refining pulverulent material the combination of a downwardly inclined screen, means for reciprocating said screen in the direction of its inclination, means for feeding material onto the upper end of said screen, brushes mounted above said screen to engage only with the material thereon, said brushes being adapted to move in the direction of reciprocation of said screen and being positioned closer to the discharge end thereof than to the feed end thereof, said brushes being arranged in rows of tufts extending transversely of said screen with the tufts in one row being staggered relative to the tufts in the adjacent rows, and means for limiting the movement of said brushes.

3. Apparatus for refining pulverulent material, said apparatus comprising a pair of vibratory structures disposed one above the other, each of said structures comprising a downwardly inclined screen and a downwardly inclined series of overlapped plates disposed below said screen with the upper end of the lower structure being adjacent the lower end of the upper structure, means for conducting material from the lower end of the upper screen to the upper end of the lower screen, and means for conducting material from the low- "er end of the upper series of overlapping plates to the upper end of the lower series of overlapping plates whereby a large vibratory area can be placed in a relatively small space, means for passing a current of air upwardly through the material being sifted by said vibratory structures, and a flue associated with the lower of said vibratory structures and being adapted to conduct a portion of the warm air to the upper of said vibratory structures without passing through the material being sifted on said lower vibratory structure.

4. Apparatus for refining cereal flour, said apparatus comprising a pair of vibratory structures disposed one above the other, each of said structures comprising a downwardly inclined screen and a downwardly inclined series of overlapped plates disposed below said screen with the upper end of the lower structure being adjacent the lower end of the upper structure, means for conducting material from the lower end of the upper screen to the upper end of the lower screen,

and means for conducting material from the lower end of the upper series of overlapping plates to the upper end of the lower series of overlapping plates whereby a large vibratory area can be placed in a relatively small space, means for passing a current of air upwardly through the material being sifted by said vibratory structures, and aflue associated with the lower of said vibratory structures and being adapted to conduct a portion of the warm air to the upper of said vibratory structures without passing through the material being sifted on said lower vibratory structure.

5. Apparatus for refining pulverulent material, said apparatus comprising a downwardly inclined screen, means for arcuately reciprocating said screen, and bristle brushes positioned above and in spaced relation to the screen and engageable with the material thereon by reason of the reciprocation of the screen, said brushes comprising a plurality of transversely directed rows of tufts with the tufts of one row being staggered relatively to the tufts in the adjacent rows the arcuate reciprocation of said screen effecting a component of vertical movement tending to toss the pulverulent material vertically upon said screen and into a crushing engagement between said bristle brushes and said screen.

6. Apparatus for refining pulverulent material, said apparatus comprising a downwardly inclined screen adapted to progressively sift a portion of pulverulent material as it passes by gravity over said screen, a series of overlapping inclined spaced apart plates arranged underneath said screen and on which said material sifting through said screen falls, means whereby a current of heated air is passed upwardly through the falling materail, the material lying on said screen, and against said plates thereby heating all the pulverulent material, means for imparting reciprocal longitudinal motion to said screen and plates whereby the gravity flow of said material is assisted, and means for discharging the material that passes through said screen into one receptacle and the remainder of the material into another receptacle, means for subjecting the material that has passed through said screen to a current of cold air as said material approaches its receptacle, whereby said material is cooled and the material which has not passed through said screen is not cooled.

'7. Apparatus for the continuous refining of pulverulent material, said apparatus comprising a housing, a downwardly inclined screen, means for delivering variable quantities of unrefined material onto said screen, means for controlling the quantity of said unrefined material delivered to said screen relative to controlled reciprocatmotion of said screen whereby the speed of refining is regulated, means for imparting a reciprocating motion to said screen whereby the gravity flow of said material over said inclined screen is facilitated and sifting of said material is effected, brushing units positioned over and spaced apart from said screen but in contact with the said material on the screen, means for actuating said bushing units in a pendulous motion whereby small lumps in the pulverulent material is subjected to a downward pressure of brushes in said brushing unit, a series of inclined overlapping plates under said screen and upon which plates at least a portion of the sifted material falls, said plates being spaced apart sufficiently to permit the passage of air therebetween, means for vibrating said inclined plates whereby the siftedmaterial flows by gravity thereover, means for drawing air into said housing andupwardly through said refiner units the air being confined to a definite channel in its passage therethrough, heated units over which the in taken air is passed and heated to a predetermined temperature, exhaustmeans for drawing said heated air between said plates and through the falling sifted material whereby said plates are heated and the falling pulverulent material is aerated and the sifted material that is falling and lying on said plates is heated and dried, said air exhaust means being adapted to draw said heated air upwardly through the sifted material lying on said screen at a velocity of air flow sufficient to cause said air to blow material of low specific gravity upwardly separating it from the higher specific gravity material, a cleaning device and means for discharging the air which carries the low specific gravity material through said cleaning device whereby the low specific gravity material is removed therefrom and the air discharged to the atmosphere, means for delivering the sifted, aerated, dried and heated pulverulent material to one receptacle and the unsifted material to a separate receptacle.

FRANK M. SMITH. 

